Does anyone know what are the advantages and disadvantages of the unitary, confederation, and the federal system of the government?

We can look at governmental systems as a continuum from a unitary type to a confederacy with federalism sitting in the middle. The unitary government is often described as a centralized government. It is a government in which all powers held by the government belong to a single, central agency. The central government creates local units of government for its own convenience.